Multistage centrifugal pump



United States Patent MULTISTAGE CENTRIFUGAL PUIWP I Josef Schellcrer,Karlsruhe, Wurttemberg-Baden, Germany Application September 5, 1950,Serial No. 183,120 Claims priority, application Germany September 10,1949 2 Claims. (Cl. 103-106) This invention relates to multi-stagecentrifugal pumps and in particular to pumps for use on fire-fightingappliances especially those including a tank.

In general, tire fighting appliances must be so constructed that theyare more or less independent of a water supply. This requirement has ledto the use of the so-called tanker fire-engine.

When a fire breaks out, and this usually occurs inside a building,prompt and effective measures are demanded. The best method is todischarge the extinguishing medium in the form of a very fine spray inthe endangered room. To produce such a spray, which causes a substantialand rapid fall in the temperature in the burning room, it is mostconvenient to employ a high pressure pump. Such a pump is known per se.If, however, lhe iire cannot be brought under control, or can only bepartially contained by the use of the spray, more vigorous action mustbe taken, and large quantities of the extinguishing medium must bedischarged. This is done by having a low-pressure stage arranged in thepump. Such devices are also known.

Multi-stage centrifugal pumps are also known, in which a high-pressurestage and a low pressure stage are provided in one and the same pump. Inthese known centrifugal pumps, however, only one pressureconnectingpiece is provided, and the high pressure stage and the lowpressure stage are each sealed by a safety valve. Furthermore, the twopump chambers are connected to each other. The communicating pipe islocated over the safety valves and consequently serves merely to connectthe high pressure chamber with the pressure-connecting piece. With suchpumps, either the high pressure or the low pressure can be used, but itis impossible to operate with both the high pressure and the lowpressure stages simultaneously.

In contradistinction thereto, the pump according to the presentinvention can operate at will at high pressure and/or low pressure fromthe suction pipe and/or from the tank since the high pressure pump andthe low pressure pump are separated from each other by a partition andare connected together by a pipe which can be opened or closed by meansof a valve.

Preferably the high pressure pump and the low pressure pump each havetheir own connecting piece for the attachment of the hose-pipes.

The arrangement of the pump is such that during operation at lowpressure, the water in the high pressure pump may be discharged to a lowpressure space, such as the atmosphere, over a reversing valve, andparticularly over the valve arranged in the connectlon pipe between thehigh and the low pressure pumps; so that the high pressure pump may rununloaded.

The tank can be filled by the low pressure pump through a branch pipe.

This new method of construction oifers a substantlal extension in themode of working as compared with 7 known centrifugal pumps and, withregard to construction, otters a substantial simplification of knowntypes.

A specific embodiment of the invention is lllustrated by way of examplein the accompanying drawing, in which the single figure shows a verticalsection through a centrifugal pump constructed according to theinvention.

In the casing 1 the impellers 3 and 4 of the pump are mounted on theoverhung shaft 2. The impeller 3 represents the low pressure pump andthe impeller 4 the high pressure pump. The widths and the diameters ofPatented Feb. 8, 1955 i the impellers 3, 4 may be in any desired ratio,for example, 1:2, 1:3 or 1:4, as a consequence of which the outputs ofthe pumps will be in the same ratio. Of course, instead of the singleimpellers 3 and 4, groups of impellers may be provided. The impellershaft 2 is drigegn from the motor shaft 7 through gearing 5, 6 anAttached to the pump casing are the suction connecting piece 9, the highpressure connection 11 provided with a control valve 11a and the lowpressure connection 10 provided with a control valve 10a. A pipe 12leading to the reversing valve 13 opens into suction connection 9. Fromthe reversing valve 13 a pipe 14 runs to a tank, not shown, so thatwater can also be drawn from the tank. A pipe 15 runs from the lowpressure pump to the valve 13 so that the tank can be refilled from thepump, the arrangement being preferably such that when the valve 13 isclosed to the pipe 12, the pipe 15 is made to communicate with the pipe14. The low pressure pump is connected to the high pressure pump by aby-pass pipe 20 in which a rotary slide valve 16 is located. A partitionwall 17 separates the high pressure pump from the low pressure pump.

A discharge passage or pipe 18 runs from the high pressure pump to theatmosphere through the body of the rotary sliding valve 16. Thus inaccordance with the position of this valve, one may connect together thehigh pressure and the low pressure pumps or isolate the pumps from eachother, or also place the high pressure pump in communication with theatmosphere.

Since interior fires are generally to be dealt with, when thefire-fighting apparatus is first brought into action the high pressurepump is used to reduce the ambient temperature by syraying thus usingonly small quantities of the extinguishing medium. So that the apparatuscan be brought into rapid operation the extinguishing medium is drawnfrom the tank of the fire engine. For this purpose the valve 16 is setso that the low pressure pump and the high pressure pump are incommunication with each other. The water then flows from thetank throughthe pipe 14, valve 13, pipe 12 and suction connection 9 into the lowpressure pump 3 and from there through the valve 16 and pipe 20 into thehigh pressure pump 4 from where it passes through the connecting pipe 11into the steel-plated hose-pipe mounted on the fire engine. Operationwith high pressure from the tank which naturally depends upon thecapacity of said tank can under usual conditions be maintained for up toabout twenty-five minutes.

Meanwhile the pipes to the hydrants, the containers, the river or thesea can be connected up so that if the fire is still unextinguished oris spreading the operation can be carried on with masses of water, thatis at low pressure. For this purpose the valve 13 is so adjusted thatthe tank is cut out and the water is sucked in through the suctionconnection 9. The rotary sliding valve 16 is also adjusted so that theconnection between the high pressure pump and the low pressure pump iscut. The water now comes from the hydrant into the suction connection 9and from thence into the low pressure pump from whence it passes throughthe connecting pipe 10 into the hose-pipe or pipes.

So that the high pressure pump should not run under load, a dischargepipe 18 is provided through which the water contained in the highpressure pump flows through the valve 16. Provided that there is anample supply of water, water can also be taken simultaneously throughthe two connecting pipes 10 and 11, and additional water can also betaken at any time from the water tank.

It frequently occurs that in accordance with prevailing conditions, forexample when a spray at high pressure and a full jet of water at lowpressure is to be produced, water must be drawn from the connecting pipe11 and the connecting pipe 10 at the same time. In this case the valve16 must be brought into the position shown in the drawing.

I claim:

1. A multi-stage centrifugal pump comprising a pump body, a partition insaid body forming two compartments 31 therein, a single suction pipe inopen and permanent communication-"with a' 'first compartment;a""low=pressure pump rotor in said first compartment, a high-pressurepump rotor in the second compartment, a common drivingigshaft fonssaidpump rotors, acommunieationpassage within-said pump .body' connectingthetwo compartments,-

a tvalveshousing formed in saidpassagqran: outlet frornthevpressurerport-ion of eaeh compartment andoperable" valve means"fora-opening and closingweach=of said i outlets, a dischargerpassage=fr'ormthe second compartment to the exterior, a section of saiddischarge passage extendingi fromnthe' said-Isecond compantment to thesaid valvenhousing and a: sectionhof saidi discharge passage extendingfrom-lathesaidfvalve housing, to the-exterior-,'

andraan operable valve in thetsaidvalve housing for opening;-andsclosing the communication passage between the compartments andat the :-same r-time closing and opening, respectively; thetsaiddischarge passage:v

2.. Annultiestage:centrifugal pump: as in: claim: 1, comprisingaaa 1rotary: valve having; a.-.transverse 1 passage: for

openlng, and;.closi-ng the rcommunication passage betweenthentwoz-icompartments, Said transverse =passage forminga section: ofthe zsaid communication: passage in: one op erating position of thevalve and forming a section of the saiddi's'charge passage from thesec0nd"'compartr'nent' in another operating positionrof the valve.

765,935: Ray: July 26, 1904 1,010,158 Lent Nov. 28,1911 1,114,230"Chapman Oct." 20," 1914 1,482,376 Anderson Feb. 5, 1924 1,782,469Havens, .Nov. v25, 1930 1,885,093" Fox Oct. 25, 1932 2,037,775., Fox:.Apr.:,2.1,' 1936.! 2,223,592 Barton Dec. 3, 1940 2,391,811 Wilhelm,Dec. 25, 1945 2,504,140 Mill Apr. 18, 1950 FOREIGN t PATENTS: 38-, 1 85Norway .May 11,.192'1j 248,601 Switzerland Feb; 16,119 15 8 766,853.France, ..Apr. .23j.1 1934--

